162 results about "Vertical seismic profile" patented technology

The invention provides a method for carrying out shale gas reservoir evaluation and finding a dessert area for shale gas exploration and development comprehensively through comprehensive application of rock physics, log data and omnibearing or wide-azimuth three-dimensional seismic data. The method is characterized by analyzing the characteristics of the dessert area in a shale reservoir by applying comprehensive geophysical exploration technologies of laboratory rock geophysical measurement, log data comprehensive analysis, rock physical modeling, vertical seismic section data, omnibearing or wide-azimuth three-dimensional seismic data high precision surface layer comprehensive modeling static correction processing, prestack de-noising processing, amplitude relative fidelity processing, resolution enhancement processing which is carried out by utilizing well constraint and well seismic data to drive ground seismic data, fine excision, iteration velocity analysis, interval velocity field analysis, prestack depth migration processing, high resolution processing, azimuth classification processing, high-precision anisotropy processing, prestack and post-stack data inversion processing, and neural network analysis and the like, and thus gas bearing characteristic prospect of the shale gas reservoir is evaluated accurately and the dessert area for shale gas exploration and development is delineated.

This invention discloses a valve that generates a hydraulic negative pressure pulse and a frequency modulator for the creation of a powerful, broadband swept impulse seismic signal at the drill bit during drilling operations. The signal can be received at monitoring points on the surface or underground locations using geophones. The time required for the seismic signal to travel from the source to the receiver directly and via reflections is used to calculate seismic velocity and other formation properties near the source and between the source and receiver. This information can be used for vertical seismic profiling of formations drilled, to check the location of the bit, or to detect the presence of abnormal pore pressure ahead of the bit. The hydraulic negative pressure pulse can also be used to enhance drilling and production of wells.

An exploration paradigm for detecting and/or characterizing gas hydrate deposits using either electromagnetic or seismic surveys, that accounts for the possibility that gas hydrate may accumulate in vertical or subvertical dikes. Geologic factors, such as the presence of the gas hydrate stability zone, indications that a prolific source of gas exists (or existed) below the gas hydrate stability zone and indications that a high flux of gas could be transported into the gas hydrate stability zone, may be considered as part of an exploration strategy. Data may be collected using seismic techniques, such as a walk-away vertical seismic profile techniques, or electromagnetic surveys that are adapted to detecting the presence of vertical or subvertical dikes. In one example, data processing and acquisition techniques may be adapted to detect hydrate dikes, and do not assume a horizontally isotropic earth model.

Embodiments of the present invention include a fiber optic seismic sensing system for permanent downhole installation. In one aspect, the present invention includes a multi-station, multi-component system for conducting seismic reservoir imaging and monitoring in a well. Permanent seismic surveys may be conducted with embodiments of the present invention, including time-lapse (4D) vertical seismic profiling (VSP) and extended micro-seismic monitoring. Embodiments of the present invention provide the ability to map fluid contacts in the reservoir using 4D VSP and to correlate micro-seismic events to gas injection and production activity.

Geophysical exploration for oil wells, the source from the vertical seismic profile aspect wave data stack depth domain Corridor profile approach is the use of in situ collection of well spacing VSP data, which will all receive points drilling depth of information and hierarchical data with the depth of information, the use of direct wave VSP data travel through and optimization algorithms are highly accurate anti-layer velocity model, the direct wave to the beginning of the reflected wave in the vicinity of the depth and precision homing imaging, further in-depth domain Corridor section and with the superposition of alternative conventional method leveled in the time domain, with corridors and the superposition method, the results can be superimposed for direct comparison with the drilling and seismic data stratified layer identification. More intuitive, but also made full use of VSP data in the depth of information, make geological formation of the earthquake response and drilling, logging data in depth domain direct contrast, a more intuitive geological layer and the relationship between seismic horizon, thereby enabling layer of identification and calibration more reliable.

The invention provides a method for optimizing a design of a vertical seismic profile observation system for seismic exploration, which comprises the following steps: establishing a seismic geological model by known data; distributing more than two different observation systems; forwarding a response of a seismic wave field; calculating a position of a reflective spot, incident and reflection angles and length or ray impact frequency, and counting characteristic parameters again to construct an analysis map; and determining the optimal scheme for actual exploration according to a geological target. The method adopts multi-parameter analysis based on a spacial model, has strong rationality of results, adapts to details, can improve data acquisition quality, is suitable for homogeneous spaces and one-dimensional, two-dimensional or three-dimensional models, can be used for non-zero spacing, Walkaway and 3D-3C VSP exploration designs, and also can be used for analyzing VSP exploration designs of longitudinal waves, transverse waves and converted waves.

The invention relates to a method for imaging an anisotropic medium through utilization of vertical seismic profile data. The method comprises the following steps: firstly, establishing an initial depth-speed model; secondly, establishing an initial speed model through utilization of an interval velocity and an anisotropic coefficient of a Walkaway VSP or three-dimensional VSP first-arrival time inversion model; converting a plane of random normal direction of a three-dimensional space into a plane with normal parallel to the Z axis; loading information of an observation system; determining a reflecting layer of which rays run through from a shooting point to a receiving point; seeking an approximate ray parameter; determining a coordinate of the reflecting point in a reflecting interface and recording the corresponding sequence number of the receiving point; determining the traveling time from the reflecting point to the receiving point and an emergence angle of the ray in the reflecting point; and outputting imaging gather data. The method simplifies calculation, has high operation efficiency, improves the precision and the resolution of the VSP imaging result and can conveniently carry out migration imaging on Walkaway VSP or three-dimensional VSP vertical wave, transverse wave or converted wave data.

Methods and apparatus facilitating logging-while-drilling (LWD) using a multi-pole acoustic transmitter source. The multi-pole transmitter source enables measurement of formation velocities, including shear wave velocities through formations that are slower than velocities through local fluids. The methods and apparatus are particularly well suited for LWD and wireline seismic surveys in which both the seismic or acoustic source and receivers are both deployed in a borehole, but may also be used for VSPs (vertical seismic profiling).

A wavefield separation method and apparatus for 3D VSP data, which handles arbitrary 3D source and receiver geometries, and common shot 3C data oriented to North, East and Vertical geographical coordinates and makes use of anisotropic medium properties at the downhole receivers. When given a range of propagation angles, slowness and polarization vectors are computed for each plane wave and a linear system is solved at each frequency to yield the scalar plane-wave amplitudes. A novel regularization scheme is used that obviates the need for eigen analysis of the steering matrix. Sums within subsets of these scalar plane waves are constructed to provide up and down qP (P), qS (Sv) and Sh wavefields. Vector residuals can be computed for parameter testing, quality control and imaging purposes.

The invention relates to a seismic horizon calibration method utilizing a vertical seismic profiling (VSP) and well-logging combination. The seismic horizon calibration method comprises the following steps: measuring and obtaining a longitudinal wave time-depth relationship and a corridor stacking profile according to zero offset data, performing well logging and obtaining acoustic well logging and density well logging data, calculating an acoustic wave time-depth relationship and a VSP time-depth relationship to get time difference, correcting an acoustic wave curve, obtaining a synthetic record through corrected well-logging curve and seismic wavelet convolution, making a horizon calibration chart after the time shift quantity of a VSP corridor and the correct polarity are determined and performing horizon calibration on a ground seismic profile according to known drilling geological stratification. According to the seismic horizon calibration method, the acoustic well logging error and the frequency dispersion effect are eliminated, the synthetic record making precision is improved, human factors in the calibration are reduced, and the calibration accuracy is improved.

The invention relates to a method for determining anisotropic parameters by utilizing the data of a three-dimensional VSP (Vertical Seismic Profile). The method comprises the following steps: when collecting the actual journey of the three-dimensional VSP, computing the time difference of each depth point; computing the anisotropic parameters of a VT I medium and the residual time difference after being corrected; determining the anisotropic parameters of an HT I medium according to the relation fitting between the residual time difference and the azimuth angle; computing the VT I anisotropic parameters of each depth point and the anisotropic parameters of the HT I medium point by point; obtaining the parameter curve of the relation that the anisotropic parameters are changed along with the depth; and eliminating the influence of the dynamic correction time difference which is changed along with the wellhead distance or the shot-geophone distance. In the method provided by the invention, the problem that the VT I anisotropic medium and the HT I anisotropic medium have the mutual interference is solved; the anisotropic influence of earthquake can be effectively eliminated; and the imaging quality of the earthquake and the prediction accuracy rate of oil gas are enhanced.

A system, method and computer-readable medium for acquiring seismic data, which includes activating a seismic source at a surface location; defining a seismic trace of a seismic wave received at a downhole location on a bottomhole assembly in a borehole in response to the activation of the seismic source; compressing the seismic trace; and recording the compressed seismic trace to a storage medium.

The invention relates to a method for improving the imaging quality of a vertical seismic profile in oil geophysical prospecting. The method comprises the following steps: picking up downlink longitudinal wave first-arrival time of different receiving points in zero-offset and nonzero-offset vertical seismic profile wave field data; establishing an aclinic initial interval speed model; pushing the first-arrival time of longitudinal wave outwards to a well side point to obtain a time field of downlink wave; seeking ray angles of downlink and uplink waves; forming a theoretical uplink wave field by utilizing the radial angle of the downlink wave and adopting a ray tracking method; obtaining a series of corresponding different interface dip angle values; and determining the maximal corresponding interface dip angle as the well side reflecting interface dip angle needing to be sought. The method can effectively reduce the influence of the estimated result of an overlying stratum on the reflecting interface dip angle and the influence of the estimated result of pickup error on the reflecting interface dip angle in the traveling of primary reflecting wave and improve the imaging quality by utilizing the vertical seismic profile.

This invention relates to a method for improving the seismic resolution in the field of petroleum exploration and development. The major problems with regard to the present low vertical seismic resolution, and the thin layer, which is recognized by the seismic data administered with difficult, may be resolved according to the present invention. This method essentially comprises the following steps of: (a) ensuring the depth and the velocity of the low-velocity layer and the high-velocity layer and the characteristic of the frequency spectrum of the seismic wave at the near-surface using the borehole-micro-logging method; (b) separating the virtual reflected wave from the seismic record in the high-velocity layer using the processing method of the vertical seismic section, and improving the SNR of the seismic record of the direct path wave at the high-velocity layer using the stack processing method of porches of the vertical seismic section; (c) evaluating the de-convolution operator of the near-surface by the convolution math-physics type equation; (d) evaluating the seismic record with high resolution by the de-convolution math-physics type equation; (e) providing the band-pass filtering and geologic interpretation to the seismic record with high resolution. Using the method of the present invention, the apparent dominant frequency may be reached to 200 Hz and higher, the vertical seismic resolution is improved, and the problem that it is difficult to recognize the thin layer by the present seismic exploration is resolved.

The invention relates to a method for inverting anisotropy parameters using variable offset vertical seismic profile data. The method includes: calculating vertical longitudinal wave speed and vertical transverse wave speed of each layer of a vertical seismic profile; collecting symbol layer positions and determining intersections of each layer and well trajectory; building up a surface layer model and an observing system; randomly initiating the anisotropy parameters of layers to be determined and cubic coefficient of a top layer interface to be determined; forming anisotropy speed models to be optimized; screening receiver inter-layer points ; collecting shot first arrival to calculate polarizing angles; building up a target function using P wave first arrival travel time and the polarizing angles; using niche genetic algorithm to optimize the target function; finishing optimization of the anisotropy parameters of the layers to be determined and configuration of the top layer interface to be determined; calculating layer by layer 'from shallow deprocessing to deep deprocessing' to finish optimization of the anisotropy parameters of the whole model. By the method, a reflecting interface is close to actual stratum, linear convergence ray tracing is high in calculation efficiency, complicated internal relations of anisotropy media are simplified, iterative test ray tracing modeling is guided by guide search of the niche genetic algorithm, and the anisotropy parameters and interface configurations are inverted and optimized nonlinearly.

The method of raising seismic signal resolution with vertical seismic profile and double micro log includes obtaining the transmission functions of seismic signal in different depth of loess tableland in low velocity layer and velocity lowering layer so as to obtain attenuation restoring filter function for restoring the received attenuated seismic signal; and using the attenuation restoring filter functions of different depth or different time to restore the received seismic signal so as to raise seismic signal resolution. The present invention provides lithologic seismic prospecting with powerful tool, and may be used in the seismic signal restoring in the area with ground of low velocity layer and velocity lowering layer.

Methods and apparatuses are disclosed for generating three dimensional (3D) vertical seismic profiles (VSPs) in a more time efficient manner. The methods and apparatuses enable faster and more efficient VSP surveys than previous techniques. Real-time updating of the velocity model and real-time reflection point density calculations are carried out, which are used to determine the location of the next seismic source firing. In the event the data of a particular bin has an insufficient fold, common image points (CIPs) or reflection point density, additional source firings may be carried out prior to moving the source. Further, in the event the data of a particular bin is excessive in terms of the fold, CIPs or reflection point density before the planned source firings for the bin are completed, remaining source firings for that bin may be skipped to save time and improve the efficiency of the data collection.